Here’s a suggestion (if you have time and the airport isn’t too far). A day or two before your flight, put the bike in the case, and go to the airport JB check-in/luggage check counter. Present it to them, explain you’re ticketed “for a flight tomorrow” (or whenever), and see if they will/would accept it. If they do…ask the JB rep if they can maybe give you a note, or something that you can present at the time you do actually check in for your flight that says the bike/case should be accepted.
Dan